Function once_spent_binding 

pub fn once_spent_binding() -> &'static str

__LGX_ONCE — the identity of every .once listener that has answered, mapped to true. An identity is the listener’s author-level address — its instance key, its static site, and its row in every enclosing {for each} — so it survives a repaint that draws the element again with a fresh node, and a spent listener stays spent however its element is redrawn.